Positioning.
Close range Sturmpios beat rifles.
Mid range it's pretty equal.
Long range Rifles beat Sturmpios.
Besides that as was said, Volley fire.
1 Rear Echelon + 1 Rifle easily beat 2 Sturmpios with Volley fire. Even one Rear Echelon sometimes manages to beat 2 Sturmpios if you know how to use it.
Whu? 1 rear echelon beats 2 Sturms? Replay please. You were either playing against the Easy AI or the guy just left. Volley fire only pins one squad (and is quasi nullified by green cover) and Sturms otherwise make mincemeat of RE in a hurry even at midrange.
Listen, I'm not talking about Sturms used by a-move newbies. People who are used to assault infantry and know how to use them can get a hell of a lot of mileage with a unit that almost has PGren level of firepower this early.
@DarthBong: What do you suggest, leaving cover and fleeing? Unless the Sturms are very far away and/or not advancing, that's asking to be shredded. It also gives up map control, which is a potentially serious loss against OKW.
I'm not saying Sturms are crazy OP, they're definitely beatable. They just seem really strong at the moment. We'll see how the meta develops, but I think it will end up with them being nerfed as well as having their price drop. Having a stronger starting unit is fine, having one that straight up beats most T1 infantry in most scenarios seems a bit much.